Development of a Test and Analysis Infrastructure for Sensors Bonded on Timepix3 ASIC

Abstract

Hybrid detectors, consisting of semiconductor sensors bonded to a readout Application-Specific Integrated Circuits (ASICs), are widely used for single-photon detection in photon science and high-energy physics. The Timepix3 readout chip provides precise Time-over-Threshold (ToT) and Time-of-Arrival (ToA) measurements, making it a valuable tool for sensor characterization.

This thesis presents the design, implementation, and validation of a complete test and analysis infrastructure for the Timepix3 readout ASIC, targeting applications in synchrotron X-ray imaging, spectroscopy, and diffraction. The research stablished a complete hardware and software pipeline, integrating electrical and energy characterization of the bonded sensors with a custom data acquisition system. This infrastructure enabled I-V measurement, automated threshold scanning, precise energy calibration, and the implementation of a novel isolated-pixel analysis algorithm that significantly improves energy resolution by mitigating
charge-sharing effects.

Validation was conducted using an Fe-55 source and monochromatic X-ray beams at the NanoMAX and FemtoMAX beamlines at MAX IV. The system successfully characterized standard silicon sensors, demonstrating high linearity essential for spectroscopic accuracy, and provided proof-of-concept validation for wire-bonded Low-Gain Avalanche Diodes (LGADs) prototypes. These results confirm the infrastructure’s capability to support future high-speed imaging and energy-dispersive spectroscopy, providing a verified platform for the deployment of bump-bonded LGAD modules in next-generation photon counting experiments.

Popular Abstract

X-rays are an invaluable tool to see inside materials without destroying them. Since Wilhelm Röntgen's accidental discovery in 1895, X-ray imaging, spectroscopy, and scattering methods have revolutionized medicine, manufacturing, industry, and security, and have become an indispensable tool across the sciences.

At the heart of this work is a highly sophisticated pixel detector chip originally developed for particle physics. Unlike conventional X-ray cameras that take images at fixed intervals, each pixel in the Timepix3 chip independently reports every detected photon, recording photons' positions, arrival times, and signal durations. Combining this information, we can indirectly measure the energy of each photon. This allows the detector to operate continuously, making it especially well-suited for experiments with scattered signals or complex timing structures, common in synchrotron and accelerator-based research.

To turn this powerful device into a working detector system, it must be coupled to a sensor that converts incoming photons into electrical charges. In this thesis, two types of sensors are studied and compared. The first is a standard silicon sensor, widely used and well-understood. The second is a newer and more experimental technology called an LGAD (Low-Gain Avalanche Diode) sensor. LGADs amplify the signal already inside the sensor, making them particularly interesting for precise timing measurements and detecting low-energy X-rays.

Before any meaningful measurements can be made, such detectors must be carefully calibrated and verified. This thesis presents the development of a complete test and validation framework for detector configuration, data acquisition, and data analysis. A custom-built software system was developed to control the detector, collect data, and process millions of individual photon events. This framework was first validated using the silicon sensor, which served as a reliable benchmark, and later tested with the LGAD sensors.

This system was tested at MAX IV Laboratory in Sweden, one of the world’s most advanced synchrotron facilities. Measurements were carried out at two experimental beamlines with very different characteristics. At NanoMAX, the detector was exposed to a stable X-ray beam, ideal for precise energy calibration and spatial characterization. At FemtoMAX, the detector faced a much tougher challenge: intense and ultra-fast X-ray pulses that push the detector systems to their limits.

The results show that the developed system can reliably measure energy, timing, and spatial information with both silicon sensors and LGAD sensors. This is a promising result for the development of future detectors.

While this work is primarily a technical study, its impact goes beyond a single detector. By establishing a robust and flexible test platform, it lays the groundwork for future developments in synchrotron science, advanced imaging, and spectroscopic systems.

• author: Shaker, Adib
• supervisor: Paul Bell; Hannah Herde; Peter Sjöblom
• organization: Department of Physics; Particle and nuclear physics
• course: FYSM64 20252
• year: 2026
• type: H2 - Master's Degree (Two Years)
• subject: Physics and Astronomy
• keywords: Timepix3, Hybrid pixel detector, X-ray sensor characterization, Energy calibration, Data acquisition system, DAQ, ASIC readout, Katherine readout device
• language: English
• id: 9220854
• date added to LUP: 2026-01-26 10:59:05
• date last changed: 2026-01-26 10:59:05